Since the discovery of quasi periodic oscillations in the light curves of magnetar giant flares, seismic vibrations of magnetars have been a subject of intense theoretical interest. A fundamental... Show moreSince the discovery of quasi periodic oscillations in the light curves of magnetar giant flares, seismic vibrations of magnetars have been a subject of intense theoretical interest. A fundamental understanding of their nature might open a new window into the poorly constrained neutron star interiors. In this thesis the physical properties of magnetar oscillations are explored from a theoretical perspective. It is shown that the presence of ultra-strong magnetic fields leads to complex dynamical behavior of these exotic objects. Show less